Circuit breaker



,L W. DYER ETAL CIRCUIT BREAKER Fil-ed Feb. 6, 1952 Jan. 19, 1954 Patented Jan. 19, 1954 CIRCUIT BREAKER Lloyd W. Dyer and Hiller D. Dorfman, Beaver,

Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a, corporation of Pennsylvania Application February 6, 1952, Serial No. 270,206

12 Claims. (Cl. 20G-116) This invention relates to circuit breakers and more particularly to circuit breakers for controlling lighting and moderate power circuits.

An object of the invention is to provide a circuit breaker having a thermally responsive trip device with means for compensating the trip device for changes in ambient temperature.

Another object of the invention is to provide a circuit breaker embodying thermally responsive trip means with means for compensating the trip device for changes in ambient temperature wherein the compensating means is mounted separate from the thermally responsive trip means.

Another object of the invention is to provide a circuit breaker embodying thermally responsive trip means and a trip member operable by the trip means to effect opening of the breaker with means mounted on said trip member for compensating said thermally responsive trip means for changes in ambient temperatures.

Another object of the invention is to provide a circuit breaker embodying thermally responsive trip means and a trip member with compensating means mounted on the trip member and engageable by the thermally responsive means to effect operation of the breaker, said compensating means compensating said thermally responsive means for changes in ambient temperatures,

The novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of several embodiments thereof when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a side elevational view, partly in section, of a circuit breaker embodying the principles of the invention,

Fig. 2 is a 'View similar to Fig. l showing a modification of the trip device applied to a somewhat different type of circuit breaker,

Fig. 3 is a sectional View taken on line III-III of Fig. l of the trip member associated with the circuit breaker illustrated in Fig. l,

Fig. 4 is a sectional view taken on line lV-IV of Fig. 2 of the trip member associated with the circuit breaker illustrated in Fig. 2.

Referring to Fig. 1 of the drawing, the circuit breaker may be of the one, two, or three-pole type and is mounted in a housing comprisinga base I and a removable cover I3, both of molded insulating material. Each pole of the breaker (only the center pole of a three-pole breaker being shown) includes a stationary contact I9, an arc extinguisher 2|, and a movable contact 23. The stationary contact I9 is mounted on the inner end of a strip 25 of conducting material, the other end of which is secured to a terminal 21.

The movable contact 23 is carried on the free end of a spring contact arm 29 which is secured to a U-shaped switch member 3|. The movable contact 23 is electrically connected by means of a flexible conductor 33, to the current responsive trip means of the trip device which will be hereinafter described. The current responsive trip means is, in turn, connected to a conducting strip 35 having a terminal 31 secured to the outer end thereof. The contacts, switch members and trip means for the three poles of this breaker are of substantially identical construction; hence only one pole has been shown and described.

The three movable switch members 3| are mounted for simultaneous movement about a common axis by means of a sectional pivot shaft 39, the center section of which is supported in the side walls of a U-shaped frame 4| secured to the base of the breaker. The switch members 3| of the outer poles (not shown) are secured to the outer sections of the pivot shaft 39, and are mechanically connected to the center pole switch members, but insulated therefrom, by insulating connecting hubs 43 (only one being shown) which connect the three separate sections of the pivot shaft together. A stop pin 45 extending through the frame 4I cooperates with projections formed on the center pole switch member 3| to limit the opening movement of the assemblage of switch members. Stops (not shown) molded integral with the cover I3 are also provided to limit the opening movement of the switch members for the outer poles.

Asingle operating mechanism is provided Afor simultaneously actuating the switch members of all three poles of thebreaker to open and closed positions. The operating mechanism is mounted in the frame 4|, and comprises a U- shaped operating member 41 having its legs pivoted on pivot members 49 struck out from the frame 4I, a releasable carrier lever 5| pivoted on a pivot pin 53 in the frame 4|, a pair of toggle links 55 and 51, and overcenter springs 59 (only one being shown). The toggle links 55 and 51 are pivotally connected together by means of a knee pivot pin 6|. The inner toggle link 55 is pivotally connected by a pivot pin B3 to the center poleswitch member 3|. 1 lThe toggle Alink 51 is pivotally connected atits' outer end by a pivot pin $5 to the releasable carrier lever 5|. The overcenter springs 59 have their outer ends connected to the bight portion of the U-shaped operating member 41, and their inner ends are connected to the knee pivot pin ti of the toggle 55-51. An operating handle 61 of molded insulating material is secured to the outer end of the operating member 41. The operating handle El is provided with a handle portion which extends through an opening 69 in the cover I3. The operating handle is also provided with an arcuate portion 1| which serves to substantially close the opening 69 in all positions of the handle. Lugs 12 are struck out from the sides of the frame 4| to limit the opening and closing movements of the operating member 41.

The breaker contacts are manually opened by clockwise movement of the operating handle from the position in which it is shown in Fig. 1. This movement carries the line of action of the overcenter springs 59 across to the right of the pivot pin 55 whereupon the force of the springs causes collapse of the toggle 55--51 thereby moving the movable contacts to the open position with a snap action. The contacts are closed by counterclockwise movement of the handle back to the Fig. 1 position. This moves the line of action of the springs 59 across to the left of the pivot pin B5, at which time the springs actuate the toggle 55-51 to its extended overset position shown, thereby moving the movable contacts to the closed position with a snap action.

The trip device of the circuit breaker includes a latch 13 pivotally mounted on a pivot pin 15 supported in the frame 4|. An extension 19 of the latch is provided with an opening 8i, one edge of which engages the free end of the carrier lever 5| and releasably restrains the carrier in normal position. The latch 13 is also provided with an extension 83 having an opening 85 therein. A trip bar 81 of molded insulating material, and common to all of the poles of the breaker, is mounted for rotation by means of a shaft 89 molded therein, the ends of which are mounted in brackets 9| (only one being shown) secured to the base I of the housing. An arcuate latch member 93 is molded into the trip bar in alignment with the opening 85 in the latch member 13. In the latching position of the parts, the carrier 5| is latched by the main latch 13 which, in turn, is held in latching position by the latch member 93. A spring 95 coiled about the pivot pin 15 biases the latch member 13 in unlatching direction and also biases the trip bar 81 to latching position. The trip bar 81 is provided. with a plurality of compensating bimetal elements 51, one for each pole of the breaker.

Each of the compensating bimetals 91 is secured to the lower side of the trip bar by means of a screw 56 and is curved upwardly around the trip bar and is provided with an integral eX- tension 98.

Each pole of the breaker is provided with an overload trip device including a tripping bimetal element IGI having a mounting foot formed at right angles thereto by which the bimetal element is secured to the base I I of the breaker, the mounting foot being secured by means of a screw |53 to a metal insert |05. At its free end, the bimetal element lill carries an adjusting screw H11 having a rounded inner end for engaging the extension 98 of the compensating bimetal element 91 and operating the trip bar t1 upon deflection of the tripping bimetal element.

The free end of the tripping bimetal element is connected to the conducting strip 35 by a ilexible conductor |99, and the :flexible conductor 33 connects the foot of the tripping bimetal element to the movable contact 23 as shown in Fig. i.

By mounting compensating bimetal element 91 on the side of the trip bar 91 opposite to, and spacing it a substantial distance from, the current responsive bimetal element lill which is heated by the current of the circuit, the compensating bimetal is largely shielded by the trip bar and is less aiiected by the heat of the current responsive bimetal element thus providing more accurate compensation for changes in ambient temperatures.

The high-expansion side of the tripping bimetal element lill is on the right-hand side thereof. Also, the high-expansion side of the compensating bimetal element S1 is on the righthand side as viewed in Fig. l; consequently the bimetal elements bend in the same direction in response to changes in the temperature of the surrounding medium, maintaining substantially the same distance between the rounded end of the screw |01 and the extension 98 of the compensating bimetal element 91 during changes in ambient temperature.

When an overload current occurs, the tripping bimetal element IBI becomes heated by the current flow and when heated a predetermined amount, bends toward the left and engages the extension 98 of the compensating bimetal element 91. Further bending of the bimetal element I 5| acts through the compensating bimetal element to cause counterclockwise rotation of the trip bar 51 and eiects release of the latch 13 whereupon the overcenter springs 59 rotate the carrier lever 5| counterclockwise. During this movement the pivot 55 is carried across to the left of the line of action of the overcenter springs which causes collapse of the toggle 55-51 and opening movement of the switch member 3| and opening of the breaker contacts..`

Before the contacts can be closed following an automatic opening operation, the carrier lever 5| must be reset to the latched position. This is effected by clockwise movement of the handle to a position slightly beyond the off position. During this movement, a projection 99 on the operating member 41 engages and moves the carrer lever 5| back to the latching position. The spring 95 then rotates the trip bar 81 to its latching position as shown in Fig. 1. The circuit breaker may then be closed by movement of the handle to the on position in the previously described manner.

Fig. 2 illustrates a modication of the invention applied to a somewhat different circuit breaker. The circuit breaker shown in Fig. 2 comprises a base and a removable cover ||3, both of molded insulating material. This breaker also is of the three-pole type (only the center pole being shown) and includes a stationary contact H9, an arc extinguisher |2| and a movable conk|4|v secured to the base l of the breaker.

`bers and trip means for the three poles of this breaker are of substantially the same construction; hence only one pole has been shown and described.

- The three switch members |29 are mounted ier simultaneous movement about a common axis by means of an insulating pivot shaft |39 pivotally mounted in the side walls of a U-shaped frame The switch members |29 of the outer poles (not shown) are secured to the ends of the pivot shaft |39.

The operating mechanism, which is similar to the operating mechanism of the circuit breaker illustrated in Fig. 1, is mounted in the U-shaped frame |4| and comprises an operating member |41 having its legs pivoted on pivot pins |49 supportedin the side members of the frame |4|, a releasable carrier lever ESI pivoted on a pin |53 in the frame Uil, a pair of toggle links |55 and |51 and an overcenter spring |59. The toggle |55|5` interconnects 'the center pole switch member |29 and the carrier lever |5| in the same manner as was described for the breaker shown in Fig. 1, and the overcenter springs |59 are connected to the knee of the toggle and to the operating member M1. An operating handle |61' is secured to the outer end of the operating member ||1l and is provided with a handle portion extending through an opening |39 in the cover i3,

The breaker contacts are manually opened by clockwise movement of the handle from the position shown in Fig. 2. This movement carries the line of action of the overcenter springs |59 across to the right of the toggle link |31 whereupon the overcenter springs cause collapse of the toggle thereby moving the switch members |29 to the open position to open the contacts. The contacts are closed by reverse movement of the handle back to the position shown in Fig. 2.

The trip device shown in Fig. 2 is mounted on its own base |5| secured by means of screws |93 to the base of the circuit breaker. The trip device includes a latch |13 pivotally mounted on a pin |15 supported in a U-shaped bracket |11 mounted on the base |9| of the trip device.

An extension |19 oi the latch |13 engages the Vfree end of the carrier lever |5| and releasably restrains the carrier lever in normal position. The latch |13 is also provided with an extension |83 which engages a latch member |93 secured to a trip bar |91 of molded insulating material. The trip bar |8'.i is common to all of the poles of the breaker and is suitably mounted for rotation. In the latching position of the parts, the

carrier lever 5| is latched by the latch 13 which is, in turn, held in latching position by the latch member |93. A spring |95 coiled about the pivot pin |15 biases the latch 13 to the latching position and a spring |9| biases the trip bar and the latch member |93 to latching position. The trip bar |81 is provided with a plurality of compenating bimetal elements |91, one for each pole of the breaker, formed from a straight strip of bimetallic material and secured to the trip bar.

Each pole oi the breaker is provided with an overload trip device including a tripping bimetal element 20|, secured to a conducting member 295 which, in turn, is secured to the base IH of the breaker by the screwT |63 by which the base iti of the trip device is secured. At its free end the compensating bimetal element |91 carries an adjusting screw 21 having an insulating button 208 on the end thereof which is engaged by the tripping bimetal upon thermal bending thereof to aotuate the trip bar 531. The free end of the tripping bimetal element 20| is connected to the conducting strip |35 by means of a flexible conductor 209 and the conducting member 205 and flexible conductor |33 connect the tripping bimetal element to the movable contact |23.

More accurate compensation of the tripping bimetal element 20| for changes in ambient temperatures is provided by spacing the compensating bimetal element |91 an appreciable distance therefrom so that the compensating bimetal element is unaffected by the heat of the current responsive tripping bimetal. The insulating button 208 also prevents transfer of heat from the current responsive bimetal 20| to the adjusting screw 201 and to the compensating bimetal.

The high-expansion sides of the tripping bimetal element 29| and the compensating bimetal element |91, respectively, are on the left-hand sides thereof. Consequently both of these elements bend in the same direction in response to changes in the temperature of the surrounding medium. This maintains a substantially constant distance between the adjusting screw 201 and the tripping bimetal element 20| as the ambient temperature varies.

Upon the occurrence of an overload current th tripping bimetal element 20| is heated by the dow of current therethrough, and when heated a predetermined amount bends toward the right to engage the adjusting screw 201 and actuate the trip bar |31. Actuation of the trip bar causes the latch member |93 to release the latch |13, whereupon the overcenter springs |59 rotate the carrier lever |5| counter-clockwise. This movement of the carrier lever |5| carries the toggle link |51 across to the left of the line of action of the overcenter springs which immediately causes collapse of the toggle V55-|51 and movement of the switch members |29 to the open position and opening of the breaker contacts.

Before the contacts can be closed following an automatic tripping operation, the carrier lever |5| must be reset to the latched position. This is accomplished by movement of the handle |61 in a clockwise direction as far as it will go. During this movement a projection |09 on the 0perating member |41 engages and moves the carrier lever back to the latching position. During the latter part of the resetting movement, the free end of the carrier lever wipes by the latch |13 which is then restored to its latching position by the spring |95. The circuit breaker may then be closed by movement of the handle to the on position in the previously described manner.

The invention provides a circuit breaker embodying a current responsive trip device and having an improved ambient temperature compensating means that is mounted away from the trip means. By this construction the compensating bimetal element is mounted an appreciable distance from the tripping bimetal element which is heated by the current of the circuit. In this manner the compensating bimetal element is unaffected by the heat of the tripping bimetal element.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement or parts thereof may be made without departing from some of the essential features of the invention.

W e claim as our invention:

l. A circuit breaker having relatively movable to effect automatic opening of said contact means,

a trip device comprising a trip member movable to release said operating means, a current responsive bimetal trip element heated in response to the current of the circuit for moving said trip member, an ambient temperature responsive bimetal element mounted on said movable trip member, and means on one of said bimetal elements cooperating with the other of said bimetal elements upon thermal bending of said current responsive bimetal element to move said trip member and effect release of said operating means.

2. A circuit breaker having relatively movable contact means and operating means releasable to effect automatic opening of said contact means, a trip device comprising a trip member rotatable to release said operating means, a current responsive bimetal trip element heated in response to the current of the circuit for rotating said trip member, an ambient temperature responsive bimetal element mounted on said rotatable trip member, and adjusting means mounted on said current responsive bimetal element and engageable With said ambient temperature responsive bimetal element upon thermal bending of said current responsive bimetal element to rotate said trip member and effect release of said operating means.

3. A circuit breaker having relatively movable contact means and operating means releasable to effect automatic opening of said contact means, a trip device comprising a trip member movable to release said operating means, a current responsive bimetal trip element heated by the current of the circuit for moving said trip member, an ambient temperature responsive bimetal element rigidly secured to said movable trip member, and an adjusting screw mounted on said ambient temperature responsive bimetal element sponsive bimetal element heated by the current of the circuit for operating said trip member, said bimetal element having one end supported and the other end free, an adjusting screw mounted in the free end of said current responsive bimetal element, and an ambient temperature responsive bimetal element having one end rigidly secured to one side of said rotatable trip member and having its free end disposed adjacent one end of said adjusting screw, thermal bending of said current responsive bimetal element causing said adjusting screw to engage said ambient temperature responsive bimetal element and rotate said trip member to effect release of said operating means.

5. A circuit breaker having relatively movable contact means and operating means releasable to effect automatic opening of said contact means, a trip member operable to release said operating means, a current responsive bimetal element heated by the current of the circuit for operating said trip member, said bimetal element having one end supported andthe other end free, -an adjusting screw mounted in the free end of said current" responsive bimetal element and extending on one side of said trip member, an ambient temperature bimetal element having one end mounted on said trip member on the side thereof away from said adjusting screw, said ambient temperature responsive bimetal element extending around said trip member and having its free end disposed adjacent said adjusting screw, and thermal bending of said current responsive bimetal element causing said adjusting screw to engage said ambient temperature responsive bimetal element and actuate said trip member to effect release of said operating means.

6. A circuit breaker having relatively movable contact means and operating means releasable to effect automatic opening of said contact means, a trip member operable to release said operating means, a current responsive bimetal element having one end supported and the other end free and extending along one side of said trip member for operating said trip member, an ambient temperature responsive bimetal element having one end rigidly supported on said trip membe on the side thereof away from said current responsive bimetal element, and means at the free end of one of said bimetal elements cooperating with the free end of the other of said bimetal elements upon thermal bending of said current responsive bimetal element to actuate said trip member and effect release of said operating means.

'7. A multi-pole circuit breaker having relatively movable contacts for each pole, operating mechanism releasable to effect automatic opening of said contacts, a trip member common to all of said poles operable to effect release of said operating mechanism, a thermally responsive bimetal element for each pole disposed to be heated in response to the current of the circuit of the associated pole, an ambient temperature responsive bimetal element for each pole, each of said ambient temperature responsive bimetal elements being mounted on said trip member, means on one of said bimetal elements in each pole, said means upon thermal bending of the current responsive bimetal element cooperating with the other bimetal element in its associated pole to operate said common trip member and effect release of said operating mechanism.

8. A multi-pole circuit breaker having relatively movable contacts for each pole, operating means releasable to effect automatic opening of said contacts, a trip member common to all of said poles operable to effect release of said operating means, a thermally responsive bimetal element for each pole disposed to be heated in response to the current of the circuit of the associated pole, an ambient temperature responsive bimetal element for each pole, said ambient temperature bimetal elements being rigidly mounted on said trip member on the side thereof opposite said current responsive bimetal elements, the end of each of said current responsive bimetal elements actuating the ambient temperature responsive bimetal element for the associated pole upon thermal bending of said thermally responsive bimetal element to operate said common trip member and effect release of said operating means.

9. A multi-pole circuit breaker having relatively movable contacts for each pole, operating mechanism releasable to effect automatic opening of said contacts, a trip member common to all of said poles operable to effect release of said operating mechanism, a thermally responsive bimetal element for each pole disposed to be heated by the current of the circuit of the associated pole, an ambient temperature responsive bimetal element for each pole rigidly mounted on said common trip member, adjusting means on said ambient temperature responsive bimetal element for each pole engageable by the thermally responsive bimetal element of the associated pole upon thermal bending of said thermally responsive bimetal element to operate said common trip member and effect release of said operating means.

10. A circuit breaker having relatively movable contact means and means releasable to effect automatic opening of said contact means, a trip device comprising a trip member movable to release said releasable means, a current responsive bimetal trip element heated in response to the current of the circuit for moving said trip member, an ambient temperature responsive bimetal element mounted on said movable trip member, an insulating member on one of said bimetal elements, and said insulating member cooperating with the other oi said bimetal elements upon thermal bending of said current responsive bimetal element to move said trip member and eiect release of said releasable means.

l1. A circuit breaker having relatively movable contact means and means releasable to eiTect automatic opening of said contact means, a trip device comprising a trip member movable to effect release of said releasable means, a current responsive bimetal element heated by the current of the circuit for moving said trip member, an ambient temperature responsive bimetal element rigidly mounted on said movable trip member,

10 means mounted on said ambient temperature responsive bimetal element, and insulating means on said means engageable by said current responsive bimetal element upon thermal bending of the latter to move said trip member and cause release of said releasable means.

12. A circuit breaker having relatively movable contact means and means releasable to effect automatic opening of said Contact means, a trip member operable to release said releasable means, a current responsive bimetal element having one end supported and the other end free and extending alcng one side of said trip member, an ambient temperature responsive bimetal element having one end rigidly supported on said trip member on the side thereof away from said current responsive bimetal element, and adjusting means mounted at the free end of one of said biinetal element having an insulating member thereon cooperating with the free end of the other of said bimetal elements upon thermal bending of said current responsive bimetal element to operate said trip member and cause release of said releasable means.

LLOYD W. DYER. HILLER D. DORFMAN.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 1,952,040 Frank et al Mar. 20, 1934 2,318,279 Aschwanden May 4, 1943 2,416,163 Dyer et al Feb. 18, 1947 

